On 17 September 2001, President Bush addressed staff at the Pentagon which was targeted along with the World Trade Center six days earlier. As he pledged that the United States would find "those evil-doers" he reminded his audience of the posters in the Old West: "Wanted, dead or alive."

By this time it was clear that the outrages were the responsibility of Osama Bin Laden's al-Qaeda organisation, then holding out in Afghanistan.

A year later, a few of the top echelon of al-Qaeda are dead or in captivity but many are assumed to be hiding in the remoter parts of Afghanistan and Pakistan. As for Bin Laden himself there is no conclusive information.

Nobody has been discovered and no claims have been made on the $25m reward. Yet at the same time there has been no evidence of activity.

Attacks thwarted

His followers wait for some sort of indication that he has not been crushed - perhaps another video to be handed to the Al Jazeera TV station or, even more effective, another terrorist spectacular.

The Americans do not claim that they have eliminated the threat of another outrage. The tenor of official comments during the summer was that it was largely a matter of "when not if".

Joseph Padilla is awaiting trial

A number of attacks have been thwarted, for example in Singapore and Morocco - and the Briton Richard Reid and the American Jose Padilla, have been apprehended.

The first task for the US is to deny the terrorists' a victory.

The first sign of such a victory would have been a decision by the United States to stay clear of conflicts involving Muslims. In fact the opposite has happened.

The massive international effort to track and detain militants can claim an important success.

The loose organisation of al-Qaeda means that activists are able to lie low or else mount operations without much support from the centre, although these may for the same reason be rather amateurish and haphazard.

Ongoing battle

In places such as Pakistan there are many militant groups so, since 11 September, attacks have been mounted against a church and French workers, while the American journalist Daniel Pearl was kidnapped and killed.

Daniel Pearl was murdered in Pakistan

Major, mass-casualty terrorist operations, of the 11 September level, probably require a degree of organisation and finance, to the extent that a number were probably in the pipeline prior to 11 September, and so would be harder to mount if the leadership of al-Qaeda is in disarray.

By declaring a general war on terror President Bush put the standards against which his campaign would be judged at a probably unattainable level.

Leaving aside the old problem of how terrorism is defined, there is no reason to suppose that violence against civilians for political purposes will suddenly go out of fashion.

It may be the case that by setting an anti-terrorist norm those groups which target civilians do not help their cause, but this may be most effective if non-violent means can be shown to be effective in redressing real grievances.

Iraq targeted

Over time the war on terror has come to be presented as passing through stages, with the first stage of pushing the Taleban regime along with al-Qaeda out of Afghanistan, and the next stage moving on to deal not so much with terrorist groups but those 'rogue' states capable of giving those groups the wherewithal to cause mass destruction using nuclear, chemical or biological devices.

The US is determined to remove Saddam Hussein

Most attention here has focused on Iraq, from where the Americans have made clear their determination to see Saddam Hussein removed from power. It is assumed that they are prepared to invade and occupy Iraq if necessary but the difficulties of such an operation have always been formidable.

The worst outcome for President Bush would be to try and fail, or gain a pyrrhic victory with Saddam Hussein - overthrown but only after many casualties all round and the Middle East in uproar.

On the other hand the continuing survival of Saddam Hussein would also be seen as a defeat for Bush (who has nonetheless said that he is prepared to be patient). Iran is also becoming more problematic in that it is acquiring nuclear reactors from Russia and has known links with radical groups such as Hezbollah.

President Bush did not in the first instance make the reconstruction of Afghanistan a goal of this war, yet for many people the removal from power of the extreme and illiberal Taleban regime was a real achievement, which needs to be consolidated through active support to the new regime.

The legacy of more than two decades of almost continual warfare has shattered the country, exaggerated the power of warlords and left much of the economy dependent upon the drugs trade.

If the negative evidence of success is the absence of terrorist spectaculars, the positive evidence may lie in a recovering Afghanistan.